Throttle position sensor (TPS): how does it work?

Statistics show that problems with the throttle position sensor often occur on VAZ 2114, 2110, 2112, Kalina, Niva Chevrolet, Priora cars. As a rule, this is indicated by error code p0120, but not always (this point is discussed in detail below). By the way, other cars are also not insured against such a breakdown.

Code p0120 means that there is a problem in the electrical circuit between the TPS and the ECU, but it does not indicate a malfunction of the device itself. Therefore, next we will talk about the signs and causes of TPS malfunction, which are typical for all cars with an injection power system.

Why is TPS needed?

Most often the sensor is a potentiometer that produces a variable resistance depending on the throttle position (and therefore the throttle position sensor).

The TPS signal is used by the engine control unit (ECM) as one of the input signals of the control system. Ignition timing and fuel injection timing (and possibly other parameters) vary depending on the throttle position, and also depending on the rate of change of this position.

Some throttle valve modifications have built-in limit switches. They are full open and fully closed throttle sensors.

How to fix a problem by cleaning the throttle body

Let's look at how to properly clean the damper step by step:

First of all, you need to get to the throttle valve. The design of different modifications of the internal combustion engine is different, but, as a rule, it is first necessary to dismantle the air duct running from the damper to the air filter.
Then you need to remove the throttle valve. You should unscrew the fastening bolts (from 2 to 4 pieces), and then disconnect all the connectors, including the one that goes to the absorber purge valve.
You can clean the throttle body using carburetor cleaner. Specialized auto chemical stores offer a wide selection of different formulations, so you can always choose the best option in terms of cost.
Thoroughly wipe the throttle body inside and out using your chosen product and a rag.
If the car is designed with a protective grille, it also needs to be cleaned.
Reassemble the assembly in reverse order.

Cleaning the throttle valve is carried out in such a way that its metal surface becomes completely light. Such cleaning will help improve the dynamic characteristics of the engine.

How to clean the throttle body without removing it

Many car enthusiasts are interested in how to clean the throttle valve without removing it. Some service stations actually offer this service, but it should be borne in mind that effective cleaning of this part can only be done after dismantling the damper.

To clean the throttle valve without removing it, use a special intake tract cleaner. In addition, this procedure can be performed using EGR valve cleaning fluid, as well as WD-40 or solvents.

Algorithm for cleaning the throttle valve without removing it:

Remove the air duct to provide access to the throttle valve.
Spray the surface of the damper, which is in the closed position, with cleaning agent and wipe with a rag.
Open the damper and clean the dirt from the side surface.
It is necessary to ensure that the cleaning agent reaches all channels (rags are also used for cleaning).

Let us note once again that high-quality cleaning of the throttle valve can only be performed after its dismantling. When installing the part after cleaning, we recommend using a new damper gasket (its cost is quite affordable).

Manufacturers of cleaning products note that the procedure for servicing throttle valves without removal should be carried out every 7,000 - 10,000 km. Cleaning the damper with removal should be carried out at intervals of 30,000 - 50,000 km.

It is important to note that in most situations, after cleaning the damper, it is necessary to adapt it. For this, a special computer is used that connects to the machine's ECU. In addition, “learning” of the throttle valve can be carried out by performing certain manipulations with the ignition and accelerator pedal. In the latter case, it is impossible to give universal instructions, since the procedure will differ for cars of different brands. You need to keep this in mind when adapting the throttle valve.

What types of throttle position sensors are there?

The throttle position sensor is mounted on the throttle body. By design, throttle position sensors are:

Contact type - with potentiometer.
Non-contact type - magnetic with Hall effect and inductive (coil).

By installation method:

Separately installed sensor.
Built into the damper drive housing.

Damper cost, service life and measures to maintain it in good condition

Prices for throttle valves vary depending on the car model and the manufacturer of the spare part. On average, their cost ranges from 3,000 to 10,000 rubles. The resource of this part is designed for the entire service life of the vehicle. The need to replace the throttle valve may arise due to breakdowns of the motor and its systems, as well as due to a faulty sensor.

Most often, improper operation of the throttle valve is caused by carbon deposits on its elements. Contamination of the remote control leads to accelerated wear of its axis and loose fit of the part in the channel. As a result, control of the volume of air entering the engine is lost. To maintain the throttle valve in working condition, it is necessary to observe the frequency of cleaning it, as well as monitor the condition of the engine and its systems.

The service for replacing the emergency protection at a service station will cost from 900 to 1,500 rubles. In addition, for adaptation of the node you will need to pay from 500 to 700 rubles. Some car repair shops may offer restoration of your car's worn-out electronics or exchange for a refurbished spare part. The price of a restored part ranges from 5,000 to 6,000 rubles.

The principle of operation of TPS with a potentiometer

The TPS sends information to the controller about idle speed, deceleration, acceleration rate and wide open throttle (WOT) status.

The TPS is a three-wire potentiometer. The first wire supplies a voltage of + 5 V to the resistive layer of the sensor, the second wire is ground. The third wire is connected to the potentiometer slider, which changes the resistance and therefore the voltage of the signal returned to the ECU.

Based on the received voltage, the control unit can calculate idle speed (below 0.7 V), full load (about 4.5 V) and throttle opening speed.

At full load, the ECU ensures that the fuel mixture is enriched. In deceleration mode (closed throttle and engine speed above certain rpm), the controller disables fuel injection. Fuel delivery is resumed when the engine speed reaches its idle speed or when the throttle valve opens. On some vehicles these values can be adjusted.

Varieties

There are two types of TPS. What are these elements? This can be a part with a mechanical or electrical drive. The first is often used on budget cars. All its constituent elements are combined into a separate block, which includes such details as:

Frame.
Throttle valve.
Sensor.
IAC (idle air control).

The damper body is included in the vehicle's cooling system. There are also pipes here that ensure the operation of gasoline vapor recovery and crankcase ventilation systems.

The idle speed regulator maintains the engine crankshaft speed when the throttle is closed during engine startup and warm-up or when additional equipment is operating. The IAC consists of a stepper motor and a valve. These two parts regulate the flow of air that enters the intake system bypassing the damper.

However, in the last few years, more and more automakers are equipping their vehicles with electrically operated throttle bodies. Such elements have their own electronic control system, which ensures the optimal amount of torque at all speed ranges and loads of the machine. This not only increases power and dynamics, but also reduces fuel consumption and exhaust emissions.

Non-contact TPS

Non-contact throttle position sensors can be of two types - with a Hall sensor and inductive.

Hall effect sensor

TPS with a Hall sensor allows you to receive a signal about the throttle position without physical contact. This makes such sensors more reliable and wear-resistant.

The Hall effect TPS consists of Hall sensors and permanent magnets that rotate around them. There is an air gap between the magnet and the Hall sensor.

The magnet is attached to the throttle shaft, whose angular movement is monitored by Hall sensors. When the damper turns, the magnets change their position.

Hall sensors detect changes in magnetic flux caused by the movement of magnets. The signal is transmitted to the circuit board, which is located in the electronic throttle body, and then to the engine control unit.

The signal sent to the ECU can be analog or digital.

Inductive sensor

Another way to measure rotational position non-contact is with a non-contact inductive type throttle position sensor. Such a TPS consists of a stator and a rotor.

The conductive rotor is a rotating part and is mounted on the throttle shaft. The rotor consists of one or more closed loops with a specific geometry, made of electrically conductive material. May be a round printed circuit board.

The sensor and board with signal processing chip are installed inside the electronic throttle body and are stationary. The stator consists of a standard printed circuit board and an application-specific integrated circuit.

The board contains the receiving excitation coils, as well as electronics for converting the input signal. When the rotor turns, a voltage is induced in the stator, which is transmitted to the ECU to determine the throttle position.

Comparison table of different types of TPS

Resistive	Inductive	Magnetic
Reliability	Contact principle, prone to wear	Contactless, good	Contactless, good
Price	Low	Average	High
Size	Big	Big	Average
Interface	Analogue only	Analog and digital	Analog and digital
Linearity	Very good	Very good	good
Reservation	Additional tracks but parallel wear	Additional tracks, sensors	Easy to install two redundant sensors

Replacing the throttle position sensor and adjusting the new device

In most cases, replacing the sensor is quite simple and you can do it yourself. The whole procedure consists of three main parts: dismantling the old faulty device, installing a new TPS, resetting the error from the ECU memory. In some cases, you will need to adjust the new device.

Actions must be carried out with the ignition off and the sensor de-energized. Unscrew the two fastening screws and remove the connector from the device. Hurray, the old sensor has been removed.

To install a new sensor, you must carefully connect the end of the throttle axis to the device seat. The holes must be aligned while turning the device in a circle. Next, you need to screw in the mounting screws and secure the connector.

To correctly reset the error from the ECU controller, you must leave the terminals disconnected from the battery for at least 8 hours. Within approximately this period, the controller's memory should be reset to zero. The most reliable option, if the first method does not help, is to contact a service center, where the problem will be corrected using a motor tester. On the other hand, you can risk continuing to use the vehicle in a “gentle mode”, hoping that sooner or later the ECU will reset the error on its own.

Signs of a malfunction of the TPS

Acceleration problems

The vehicle lacks power when accelerating or accelerates spontaneously. It may seem like the car just isn't accelerating as well as it should.

The car jerks when it picks up speed. Acceleration may be smooth, but it lacks power.

It may happen that the car suddenly accelerates on its own, even if you have not pressed the gas pedal. If these symptoms occur, there is a good chance that you have a TSD problem.

Floating idle

If you experience engine misfire, floating idle, or stalling, this could also be a sign of a faulty TPS.

This means that the control unit cannot detect a completely closed throttle, i.e. the idle mode is disabled. The TPS may also send incorrect data, causing the engine to stop at any time.

Reduced maximum speed

The car accelerates, but does not exceed a relatively low speed. This is another throttle position sensor failure mode that indicates that it is falsely limiting the power requested by the accelerator pedal.

You may find that your car will accelerate, but not more than 30-50 km per hour. This symptom is often accompanied by a decrease in power.

Check Engine

Check to see if the Check Engine Light comes on, accompanied by any of the following symptoms.

The check engine light may come on if you are having problems with the TPS. However, this is not always the case, so don't wait for the CE light to come on if you notice any of the above symptoms.

Check the vehicle for trouble codes to determine the cause of the problem. This can be done using a diagnostic scanner or an ELM327 adapter with Torque software.

Causes of malfunction of contact sensors

The main reason for failure is wear of the resistive tracks, leading to a complete or partial break in the electrical circuit. This leads to the transmission of incorrect data to the ECU.

Causes of malfunction of contact sensors:

Wear of the resistor layer leads to loss of electrical contact. This can happen either at the beginning of the slider’s movement (typically when the voltage at the sensor output is low), or on another section of the tracks.
Broken or worn tip.
Wear of drive gears.
Short circuit of signal or electrical circuits.
Broken wiring, especially for VAZ cars, whose wires are not reliable.
Oxidation of contacts and contamination of connectors.

Most causes can be diagnosed visually after disassembling the device and using a multimeter.

Regarding error P2135, which was mentioned in the previous section, its causes:

poor ECU contact ground;
oxidation of contacts in the connector;
main relay malfunction;
short circuit and other reasons.

How to check TPS

Here we will talk about how to test throttle sensors, what malfunctions may occur and how to identify them.

Voltage check

Connect the black lead (negative) of the digital multimeter to the case or negative of the battery.
Locate the reference voltage (+5 volts), ground, and signal voltage terminals.
Most throttle potentiometers have three terminals, but some may have additional terminals that function as throttle ends.
Connect the multimeter's red lead (positive) to the signal voltage terminal.
Turn on the ignition, but do not start the engine. In most vehicles the voltage reading should be less than 0.7V.
Open and close the throttle valve several times, checking that the voltage changes smoothly.

Checking the sensor resistance

Disconnect the sensor connector.
Connect a multimeter in resistance measurement mode (Ohms) between the potentiometer slider terminal and the reference voltage terminal. Or between the runner and the ground.
Open and close the throttle valve several times and check for a smooth change in resistance. If the potentiometer resistance is infinite or zero, this indicates a malfunction.
We do not indicate the exact resistance values of the potentiometer. One reason is that many manufacturers do not publish benchmark data. The fact that the resistance of the potentiometer is within certain limits is less important than the correct operation of the potentiometer, that is, a smooth change in resistance when the throttle valve is moved.
Connect the multimeter between ground and the reference voltage pin. The resistance must be constant.
If the resistance is infinite or small, the potentiometer must be replaced.

Checking the performance of the TPS

If during operation of the vehicle at least one of the signs of malfunction of the throttle position sensor was detected, its functionality must be checked. To do this, the car owner does not require any special knowledge. It is enough to have a multimeter and know a clear sequence of actions.

The main thing to remember is that the Check Engine is a light that is installed specifically to signal the driver about a faulty engine. If it lights up, then you need to immediately contact a service station or fix the problem yourself.

If there are no problems, the light will light up when the engine starts and go out instantly when the diagnosis is complete. If the Check Engine light remains on, there is a problem with the system. In this case, you cannot do without an experienced specialist.

Regarding the identification of throttle valve malfunctions, the symptoms of which were identified during the operation of the car, there is a certain algorithm of actions:

The first thing you need to do is turn off the ignition, inspect the instrument panel, notice whether the Check Engine indicator light is on or not, which signals the presence of problems. If the indicator does not light up, you need to climb under the hood and check the TPS.
Next, you will need a multimeter - a special device to check the operation of the throttle sensor.
It is necessary to determine the presence of a “minus”. In order not to discard each wire separately, it is worth piercing the necessary wires and measuring them.
The search for “mass” is carried out in the same way. There is no need to turn on the ignition during the mechanism check period.

The purpose of performing preliminary actions is to check the availability of power to the PD sensor. The voltage depends on the make of the car. For example, for some machines it may be only 5 V, while for other models it may be 12 V.

Algorithm of actions for identifying TPS faults, the symptoms of which were identified while the vehicle was moving:

you need to turn on the ignition and pierce the wires of the required chain one by one using a multimeter. The device display should show a voltage reading of 0.7 V;
the throttle valve opens manually: the voltage value must be greater than 4 V;
The ignition is turned off, one connector is discarded. In the area between the slider terminal and the wire (which remains), a multimeter probe is connected;
Now you need to manually scroll the sector and observe the readings of the measuring device. If there is a smooth increase in values without sudden jumps, it means that the PD sensor is working normally. In the opposite situation, we can talk about damage (scuffing) of the resistor track.

These indicators affect the proper functioning of the electronic control unit (ECU), which controls the main operating processes of a car engine and the supply of fuel mixture to the injectors. If inaccurate numbers are supplied to the ECU, then the control unit will make incorrect decisions.

For example, the throttle valve is fully open, but the electronic device shows that it is closed. If such symptoms are present, this is an obvious malfunction of the throttle sensor and must be replaced.

Troubleshooting throttle position sensor

Chaotic output signal

The signal voltage changes sharply and may drop to zero. When the throttle sensor output is erratic, it is usually caused by a faulty potentiometer. In this case, the sensor must be replaced.

No voltage signal

Check the presence of reference voltage (+5.0 V) on the connector.
Check the condition of the potentiometer ground contact.
Check the signal wire connecting the sensor to the control unit.
If problems are found with the reference voltage and grounding, check the continuity of the wires between the TPS and the ECU.
If the sensor wires are OK, check all power and ground connections to the controller. If everything is fine with them, the most likely cause is the control unit itself.

Differences between an electric damper

How does this part differ from its mechanical counterparts? Its main differences lie in the absence of a mechanical connection between the gas pedal and the throttle valve, as well as in the regulation of idle speed by moving the damper itself.

But that's not all of its features. Since there is no rigid connection between the gas pedal and the throttle valve, the electronic system itself can influence the amount of torque of the internal combustion engine, even if the driver does not press the accelerator. All these changes occur due to the actions of the input sensors, control unit and actuator.

In addition to the TPS, the electronic control system contains an accelerator pedal position sensor, as well as a brake and clutch position switch. Thus, the engine control unit responds to all signals from the sensors and converts these impulses into control actions on the damper module.

Replacing TPS

Removing the sensor from the car is necessary to install a new one. First of all, you need to turn off the electrical power by disconnecting the battery terminals. The wires that are connected to the device also need to be disconnected. After unscrewing the mounting bolts, the TPS can be removed. When installing a new, original spare part, no adjustment is required.
Direct installation of a new device. To begin with, the spare part is connected to the electronic control unit, after which the terminal is put on the battery. With this algorithm of actions, all factory settings will be saved. Attention: it is important to install only original devices. A sensor from another car model is not suitable. The necessary device can be purchased in special stores or from an official representative of the car brand. Buying online or on the market most often leads to the acquisition of counterfeit goods. The choice of seller should be taken carefully and seriously.

Do-it-yourself TPS restoration

Graphite glue
I decided to remove and disassemble the sensor to check the integrity of the graphite tracks by eye. Having taken it apart, I saw that the graphite tracks were indeed erased; I cannot determine the degree of wear. It was decided to purchase graphite glue to restore the board tracks. I found the most suitable one in the Chip and Dip store, costing 150 rubles.

Restoring sensor tracks with graphite glue.

I removed the damper sensor and carefully cut it with a hacksaw because... There is no other way to open it, I carefully bent the board and applied a thin layer of glue to the tracks. I assembled and glued everything together, all that remained was to adjust the throttle position sensor, which I actually couldn’t do myself, even with a diagnostic adapter, a multimeter and probes on hand.

The next day I went to the service station to adjust the throttle position sensor. The slipping of the car was terrible; when changing gears in different positions, the revolutions jumped from 2500 to 4000 thousand.

The photo shows very worn tracks

At 100, the technician reset everything to the car’s factory settings and adjusted the throttle position. At idle everything was fine, but on the way home I noticed slipping from 2nd to 3rd gear. It wasn’t strong, for example, if switching occurs at 1800 it increases to 2000, if at 1700 it increases to 1900 thousand, but if you apply gas this does not happen.

I started reading because I had thoughts in my head about burnt (worn out) clutches because... On the day of visiting the service station, I had to drive for a couple of hours with terrible slippage, but soon I immediately discarded this reason.

I called the service station and again spoke in detail about the problem, the master suggested that I check the wiring and automatic transmission, and not blame the damper sensor, since I was only thinking about it, I went to disassemble it again.

The method that helped

This time, I did not remove the throttle position sensor itself, so as not to have to go adjust it again, but removed the damper completely from the car, bent the board with the tracks and carefully cleaned it of the graphite glue that I had applied before.

Inside the TPS there are graphite tracks along which the brushes move. The most effective way to repair

- this is to bend these brushes to the sides along a whole part of the paths, this must be done very carefully, I used thin tweezers and flat tweezers.
Don’t think of degreasing the tracks or lubricating them with anything special using cotton swabs and sponges. These brushes need to be carefully bent.
This time, I planned to solve the problem

bending the brushes onto entire parts of the TPD tracks. I assembled it, started it and went to check it out. The ride is smooth, there is no slipping, the speed remains at 1400, 1650 at 1900 thousand, etc. in general, everything is as it should be, you can make the repair yourself and revive the damper sensor before buying a new one, the main thing is to do everything carefully and slowly.